Recently, services, such as social networking services (SNS), that share content between particular users are increasing. Moreover, as a result of it now being possible to generate high image quality content due to the increasingly high functionality of terminals, the size of shared content is ballooning, with a tendency for the waiting times for uploading and downloading content to get longer.
Methods that employ cache servers are widely utilized as methods to shorten the waiting times for uploading and downloading content. For example, for content accessed by an unspecified large number of users under management of a cache server, frequently accessed content is distributed to that cache server. This thereby enables the time taken to download content to be shortened for users under management of that cache server.
Moreover, a multicast broadcasting method that prepares an in-use content server and a standby content server has been proposed as technology related to content broadcasting. In this method, the in-use content server broadcasts multicast content, and the standby content server joins corresponding multicast groups, receives multicast packets in which in-use content is transmitted, and monitors the broadcast status of the in-use content server. Moreover, content broadcasting completion information (content duration, sequence number information, absolute completion time information) is registered for each item of content. Based on the broadcast completion time, prior to the predicted broadcast completion of the content, the absence of multicast packets arriving from the in-use content server triggers the initiation of multicast broadcasting of the corresponding content by the standby server.
Technology like that below has also been proposed in relation to transmission of large files. For example, a file transmission device has been proposed that includes a statistical information storing means that stores statistical information, a file storing means that stores files, and a path selection means that selects a control path and a data path based on a settings file or a selection rule. This device further includes a control message processing means that processes control messages, a file management means that segments files and allocates sequence numbers, a file transmission means that transmits files, and an IP transmitting means that performs IP transmission processing for the files.